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Advisory record · GHSA-8v84-f9pq-wr9x

Pillow `PcfFontFile._load_bitmaps()`: `Image.frombytes()` called without `_decompression_bomb_check()` — bomb protection bypass via PCF font loading

CVSS 7.5 HighEPSS 0.0041 · 35th percentile

Published by the GitHub Advisory Database at 20 Jul 2026, 21:08 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

PackageEcosystemAffectedFixed in
pillowPyPI<12.3.012.3.0
Identifiers
GHSA-8v84-f9pq-wr9x · BIT-pillow-2026-54059 · CVE-2026-54059 · PYSEC-2026-2253
Weakness (CWE)
CWE-789
Tags
Published
20 Jul 2026
Updated
10 Sept 2026

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

Pillow versions before 12.3.0 are affected: when loading PCF font files, PcfFontFile._load_bitmaps() skips Pillow's decompression bomb check, so glyph images can be allocated far beyond the normal size limit. An attacker who can get an application to load a crafted PCF font from an untrusted source can cause large memory allocations, leading to denial of service. Upgrade to Pillow 12.3.0 or later, which contains the fix; the source does not list a workaround.

Written 1 Nov 2026.

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

ScoreRatingCVSSVectorSource
7.5 High 3.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H CNA (GitHub_M)
  • CISA KEV Not listed.
  • EPSS 0.0041, the 35th percentile, on 15 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

  1. 3 Jul 2026, 08:33 UTC Published by the maintainers as a GitHub repository advisory
  2. 31 Oct 2026, 14:11 UTC First seen by agentprime
  3. 31 Oct 2026, 14:11 UTC Confirmed by OSV

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.